The invention relates to a welding head for heated tool welding, particularly of thermoplastic materials.
Welding heads for heated tool welding are known, which have a gripper for holding the welding part. In addition, on the welding head is located a double-acting welding mirror, which is used for heating the welding point on the body onto which the welding part is welded. Following the heating of the welding point the welding mirror can be brought by a drive means out of its position between the welding part and the body, so that the welding part can be engaged with the body.
Such welding heads are used for various forms of heated tool welding, particularly in the case of thermoplastic materials. One field of use of heated tool welding is the welding on of welding parts to bodies made as blown parts, e.g. fuel tanks for motor vehicles.
Welding heads with double-acting welding mirrors suffer from the disadvantage that there is a heating of the welding points both on the body and on the welding part in simultaneous manner and which is always of the same time duration. Thus, when using different thermoplastic materials for the body and welding part, it is difficult to take account of the different premelting and melting on times of different thermoplastic materials.
The problem of the invention is to provide a welding head for heated tool welding, which permits an independent heating of the welding point on the body and the welding part.
According to the invention this problem is solved by a welding head having the features of claim 1.
Such a welding head for heated tool welding, particularly of thermoplastic materials, has a gripper for receiving the welding part to be welded to the body. It also has a first welding mirror for heating the welding point on the body. A second welding mirror is used for heating the welding point on the welding part. The first welding mirror and the gripper are placed on a common supporting member, which is so displaceable by drive means that alternately the first welding mirror and the gripper are oriented towards the welding point on the body.
Thus, according to the invention, there are two separate welding mirrors, the first of the two welding mirrors being used for heating the welding point on the body and alternatively for heating the welding part. This permits an independent heating of the welding part and the body in the vicinity of the particular welding point. Thus, different thermoplastics can also be welded together and a good welded joint quality is ensured. The quality of such a welded joint is measured against its rigidity and strength, as well as its tightness.
According to a preferred development of the welding head the supporting member is pivoted. According to another preferred development the pivoting of the supporting member with the first welding mirror and the gripper takes place about an axis, which is at right angles to the connecting line between gripper and first welding mirror and which face one another on the supporting member. The angle by which the supporting member is pivoted is 180xc2x0.
Such a construction has the advantage that the welding head can be made very small and only a limited movement space is required. As a result the welding head can be used more flexibly, e.g. also at less accessible welding points.
According to another preferred development of the invention the second welding mirror can be engaged with the welding part held in the gripper when the first welding mirror is oriented towards the body.
According to another preferred development the second welding mirror is moved from its engagement position with the welding part into a non-engagement position and back again.
According to another preferred development the movement of the second welding mirror takes place with respect to the supporting member.
It is also advantageous to place the supporting member and the second welding mirror with its displacement drive on a common base plate. Preference is also given to the development in which the base plate has on its side remote from the supporting member coupling points for the in particular automatic coupling and uncoupling of the base plate with respect to a robot arm.
This makes it possible to place the welding head in very simple manner on the actuator unit, preferably an industrial robot. Thus, with a single infeeding member different welding heads can be driven and consequently varied welding parts can be welded to a single body. As a result of these measures the setting up times for changing the welding head are reduced.
Preference is also given to the development in which the gripper for the welding part can in particular be automatically replaced. This makes it possible to use different grippers for different welding parts, provided that the welding parts can be heated with the same welding mirrors. This makes it possible with the same welding head to react more flexibly to the demands of the welding parts.
It is possible to drive the drive means for the displacement of the supporting member with the gripper and first welding mirror, as well as the linear controlling element for driving the second welding mirror both electrically and/or pneumatically.
According to a preferred development of the invention the welding head is constructed as the final effector of an industrial robot.